TREML4 (Triggering receptor expressed on myeloid cells-like 4; also TLT4) is a 53-55 kDa member of the Ig superfamily. It is likely expressed by leukocytes, and based on its structure, may act as an activating receptor. Mature mouse TREML4 is a type I transmembrane (TM) glycoprotein that is 235 amino acids (aa) in length. It contains a 171 aa extracellular region (aa 29-199) with a V-type Ig-like domain (aa 29-122); the TM segment contains one